Simultaneous stretching and corona poling of PVDF and P(VDF-TriFE) films. II

Abstract

For pt.I see T. Kaura, R. Nath and M.M. Perlman, ibid., vol.24, p.1848 (1991). Copolymer films of 75/25 and 50/50 mol.% poly(vinylidene fluoride-trifluorethylene) P(VDF-TriFE) are simultaneously stretched and corona poled (SSCP) in batch mode at elevated temperatures. When poled under optimum conditions, the 75/25 films yield a piezo-electric constant d31 approximately 48 pC N-1 and a pyro-electric constant p approximately 5 nC cm-2 K-1, at 30 degrees C. Both of these values are about 1.7 times those reported for films that were poled after stretching and agree with previously predicted, but until now unobserved, maxima. A 'frozen-in' stress limits the beta phase content and hence the piezo- and pyro-activity in normally drawn films. Drawing at elevated temperatures during SSCP raises the yield level, and hence the ultimate activity. The stability of d31 was also improved by SSCP. The authors postulate that there is a contribution of ferroelectric domain rotation in these SSCP films. X-rays show that they have an enhanced beta phase over those that were poled after stretching. The 50/50 films yield roughly the same activities (d31 approximately 35-40 pC N-1 and p approximately 4.8 nC cm-2 K-1 at 30 degrees C) whether poled during or after stretching, in agreement with the maximum values obtained by others and predicted by the authors. A good correlation with dipole moment was found amongst the activities of the copolymers and 100% PVDF.

Hybrid lead-free polymer-based nanocomposites with improved piezoelectric response for biomedical energy-harvesting applications: A review

“…Contact-mode poling with an electric field and heating is illustrated schematically in Figure S2. The applied external electric field strength required to achieve permanent polarization of PVDF has been reported to be 100 MV/m [144], 300 MV/m [145], 220 MV/m [146], 2.7±0.1 MV·m -1 [35], and 20 V·μm -1 [147]. The poling conditions were as follows: 50 kV cm −1 was applied at 100 °C to PVDF-TrFE containing BTO and rGO [33].…”

Characterisation of Pyroelectric Materials

“…The field and the duty cycle need to be optimised for the individual material. • Corona poling [27] is a technique which has been successfully applied to polymeric ferroelectrics such as PVDF. It consists of exposing one, nonelectroded, face of the ferroelectric to a corona discharge from a series of metal points held at high voltage (typically >10KV).…”

Optimization, characterization and evaluation of ZnO/polyvinylidene fluoride nanocomposites for orthopedic applications: improved antibacterial ability and promoted osteoblast growth

“…Polyvinylidene fluoride (PVDF) possessed good resistance to chemical corrosion, high temperature, oxidation, radiation and it also has piezoelectric, dielectric, thermoelectric and other special properties making it suitable for orthopedic applications. Moreover, the transformation among various PVDF crystal shapes can be achieved (Agarwal et al., 2008 ; Noriega et al., 2012 ) so that the PVDF materials with optimal crystal shapes can be prepared according to implant needs (Kumar & Periman, 1993 ; Lin et al., 2004 ). PVDF is considered as a potential bone tissue engineering material because of its piezoelectricity (just like bone) and biocompatibility, however, its applications in the body have been limited in that it has no ability to resist bacteria growth or infection (Rim et al., 2013 ).…”